Has anyone ever come across an Operators Manual or a Parts List specific to the D4-12? I have manuals for the D4-10 and the HD-12. I have even asked the good folks at Bush Hog, but they sent one for the HD-12.

Like Brian and Daniel, never seen one and don't think they made one either. But like Daniel, I think the D4-10 manuals were given with the D4-12's when they were sold.
On the D-series tractors there were T-63; then D4-7; then D4-7 and D4-10; then D4-10 manuals. I think they may have made an earlier version and then an updated version of the D4-10 manuals and possibly the T-63 manuals.

From what I can tell and from talking to the factory manager, the HW-12 was just a HD-12 with the "wide tires" option. If you notice George's HD-12 has the 26-12-12 rear tires and 20-8-10 front tires, my HD-12 came with 15" rims in the back and 12" rims in the front. I have since converted my HD-12 to a HW-12 by putting on the Good Year Terra Ags 26-12-12 and the 20-8-10 tires on the front.